Low Field MRI Findings of the Morel-Lavallée Lesions in the Soft Tissue of the Limbs

Objective: To analyze the low field MRI findings of the Morel-Lavallée Lesions in the limb soft tissue. Methods: A retrospective analysis of 0.35 T MRI data of 29 cases with the Morel-Lavallée Lesions confirmed clinicly in the limb soft tissue.Results:29 patients with 35 lesions, mainly involving locations(cases): around the knee joint(n = 12), pelvis and upper leg(n = 10), crus(n = 4), upper arm(n = 2) and forearm(n = 1). The lesions(numbers, n = 35) were located between deep subcutaneous fat and deep fascia, with oval(n = 5), fusiform(n = 11) or crescentic(n = 19) and may have tapering margins that fuse with adjacent fascial planes. The lesions were well defined with no capsule(n = 21), a portion of the capsule(n = 10) or complete capsule(n = 4), partially with separation(n = 9). The lesions may be characterized by a variety of signal features due to the internal composition and content of the fibrous tissue and/or blood: in the acute and subacute phase(n = 3), the lesions mainly composed of bloody component(MRI showed high T1WI and high T2WI signal), in the chronic phase(n = 26), the lesions mainly composed of liquid(MRI showed low T1WI and high T2WI signal). The strip, small article or flake fat signals may be seen within the lesions(n = 23), partly with liquid-liquid flat and fat-liquid flat(n = 10). Conclusion: MRI is a important non-invasive examination method to evaluate the Morel-Lavallée Lesions of the limb soft tissue.